Regenerative Braking

[strider]

If you're interested in seeing when the brake lights turn on, touch the Tesla symbol on the center console and when you let of the accelerator the image of the car on the screen will depicte the brake lights. This will confirm whether the brake light is actually coming on or not when letting off the accelerator. Based on what you learn, you may need to provide more space between yourself and the car in front to avoid excessive brake lights.

My point is that I don't care. I have been driving a Roadster for almost 3 years and I just DRIVE IT. My wife has driven her MS for 8 months and just DRIVES IT. Stop overthinking it. No one has rear-ended me nor have they flipped me off for excessive brake light usage.

If you drive an ICE aggressively you're going to flash your brake lights a lot. If you drive a Tesla aggressively you're going to flash your brake lights a lot. End of story. Tesla has spent a lot of time to refine the brake light algorithm. Just let it do its thing.

The problem I keep getting hung up on is how do you enforce some sort of consistency across different vehicles, and brakes in various states of repair. I can see a slowing/stopping interstate having people show barely braking, while others seem maxed out.

It would have to be based on intensity only as that would be something simple for the DOT to measure vs trying to do something with segments or whatever.

 

[MarkR]

Maybe it has been discussed elsewhere, but I haven't seen it . . . I, like most Tesla drivers, enjoy one-pedal driving and strive to avoid touching the brake pedal. I want to regenerate as much power as possible. I'd like to humbly suggest that Tesla could make regenerating power even more efficient if depressing the brake pedal initially triggered aggressive power regeneration. Think about it . . . we could regenerate more power if the amount of pressure on the brake pedal determined the aggressiveness of regeneration. I'm no engineer, but it makes sense to me.

 

[Electroman]

That is exactly how Leaf works and possibly Volt and every other EVs out there.

In their infinite wisdom Tesla chose not to regenerate while braking. No idea why.

 

[neroden]

That is exactly how Leaf works and possibly Volt and every other EVs out there.

In their infinite wisdom Tesla chose not to regenerate while braking. No idea why.

(1) It makes for a much simpler mechanical/electric design.
(2) It drives more clearly and cleanly, at least to anyone who's ever driven a stick shift.

It was the right choice. I find regen is maxed out all the time just from lifting my foot off the pedal anyway, in cold weather when there's a permanent regen limit at 30.

 

[jerry33]

Maybe it has been discussed elsewhere, but I haven't seen it . . . I, like most Tesla drivers, enjoy one-pedal driving and strive to avoid touching the brake pedal. I want to regenerate as much power as possible. I'd like to humbly suggest that Tesla could make regenerating power even more efficient if depressing the brake pedal initially triggered aggressive power regeneration. Think about it . . . we could regenerate more power if the amount of pressure on the brake pedal determined the aggressiveness of regeneration. I'm no engineer, but it makes sense to me.

The maximum amount the system is capable of without excessive tire wear is the maximum amount. You either have to divide the regeneration up between pedals and work out a complex control system or have it all on one pedal but you won't get even one iota more of regeneration. In addition, stopping distances will increase because maximum regeneration wouldn't start until you depress the brake pedal. Having it all on one pedal simplifies design and eliminates the transition hiccup found on other cars (The 2010 Prius had a recall for this because folks complained so much, and it was a common topic on the Prius boards long before 2010.)

Having it all on the accelerator pedal is a much more elegant, fool proof, and cost effective implementation for regenerative braking.

 

[Electroman]

Cost effective? Fool proof? Easy design ?

Over a 100k Leafs and Volts worldwide have had no issues and I drive a Leaf and with close to 30k miles in it, I can tell you from a driving perspective you simply cannot tell the difference as to when the friction brakes are engaged.

Simply put there is no reason to waste any energy to heat and friction, especially given that Model S is quite heavy there is a lot of Kinetic energy that is thrown away.

 

[wycolo]

> Tesla chose not to regenerate while braking. No idea why. [mkj . . ]

You imply that regen is turned OFF as soon as brake light switch makes contact. This certainly is not true. You must mean that hitting the brake does not ADD to regen level, ala Prius (I'm not a Prius follower).

Btw, since ~March 2013 upgrade MS has 2 tier regen such that once you slow to ~8mph (a guess) on the wimpy regen it then hits max regen for the rest of the way to zero. This with not pressing brake and REGEN set to max.
--

 

[Dreamin]

Single biggest reason a dumped my Prius. Hated the brakes: Very non-linear, impossible to modulate, and just plain felt like crap. Of course in a 10sec 0-60 car, you can't get yourself into too much trouble.

I would not have purchased the Tesla if any of the regen was associated with the braking system.

 

[rlcordeiro]

People have been complaining that regen with 5.8 is lower than before and are pushing a 2 change and 2 reboot solution. Anybody know if this is a bug or intentional change.

 

[Fredly]

People have been complaining that regen with 5.8 is lower than before and are pushing a 2 change and 2 reboot solution. Anybody know if this is a bug or intentional change.

I rebooted as soon as I upgraded and regen is exactly the same.

 

[jcaspar]

Having driven a Leaf and my Model S, I much prefer the driving style of the Model S. Very intuitive if you are used to driving a stick shift. I really dislike the brakes on the Leaf and the Prius is known for having poor brakes.

 

[strider]

Cost effective? Fool proof? Easy design ?

Over a 100k Leafs and Volts worldwide have had no issues and I drive a Leaf and with close to 30k miles in it, I can tell you from a driving perspective you simply cannot tell the difference as to when the friction brakes are engaged.

Simply put there is no reason to waste any energy to heat and friction, especially given that Model S is quite heavy there is a lot of Kinetic energy that is thrown away.

To reiterate jerry33, if you lift the throttle all the way on a Model S you ARE at full regen. That is the maximum amount of power the batteries/electronics can accept and/or the tires have traction to deliver. So in the case of the Volt or Leaf they give you some % of the total on the throttle and the rest on the brake. Those cars do not have more regen than Model S. Your statement that energy is being wasted to heat and friction is simply WRONG. From my super-short web search people believe the Volt is capable of 60kW of regen so it's the same as Model S. And in the Leaf it seems like it maxes at 30kW but a recent software update has limited it to 15-20kW (queue Twilight Zone music): My Nissan Leaf Forum View topic - What happened to my Regen?

Keeping it separate is the best way. This way you're not constantly dancing your foot back and forth between the throttle and brake. I commute in crazy traffic every day and almost never have to move my foot to the brake.

- - - Updated - - -

People have been complaining that regen with 5.8 is lower than before and are pushing a 2 change and 2 reboot solution. Anybody know if this is a bug or intentional change.

Regen is not lower in 5.8. It is engaged more gradually so if you lift suddenly you won't throw your passengers forward. Total amount of regen is the same.

 

[contaygious]

After i reset my screen regen went back to normal so crossing my fingers it was a bug with 5.8

 

[rlcordeiro]

Regen is not lower in 5.8. It is engaged more gradually so if you lift suddenly you won't throw your passengers forward. Total amount of regen is the same.

Ah the beauty of OTA updates!

 

[spleen]

Cost effective? Fool proof? Easy design ?

Over a 100k Leafs and Volts worldwide have had no issues and I drive a Leaf and with close to 30k miles in it, I can tell you from a driving perspective you simply cannot tell the difference as to when the friction brakes are engaged.

Simply put there is no reason to waste any energy to heat and friction, especially given that Model S is quite heavy there is a lot of Kinetic energy that is thrown away.

I disagree - I've driven a Leaf for over 25,000 miles and I can tell the difference when regen stops and the friction brakes kick in. I prefer the simplicity and better feel of the Tesla. And as others say, max regen is max regen - you can't get more by putting it on the brake.

 

[neroden]

No, I don't think that's accurate. I just like to be "crisp" with my driving, if that makes sense. If there's a guy going 65 mph a 200 feet in front of me and I'm also going 65 mph, but I'd rather be 40 feet behind him instead of 200

IIRC, safe following distance increases as the square of the speed, so you really should be 200 feet behind him!

 

[jerry33]

IIRC, safe following distance increases as the square of the speed, so you really should be 200 feet behind him!

The question is, "Who can correctly estimate 200 feet?". Seconds is what should be used because it's reaction time that counts, and the distance automatically goes up with the square of the speed. 3 - 4 seconds is the recommendation. 2 seconds is cutting it close.

 

[Al Sherman]

The question is, "Who can correctly estimate 200 feet?". Seconds is what should be used because it's reaction time that counts, and the distance automatically goes up with the square of the speed. 3 - 4 seconds is the recommendation. 2 seconds is cutting it close.

No question. Reaction time. The vast majority of drivers follow too closely for their given speed. In big jets the FAA computes 3 seconds (at speed) into the stopping distance time on an aborted takeoff for the pilot to recognize the need for an abort and apply full braking, and idle power.

On crowded interstates in and around most big cities it's almost impossible to follow far enough behind. On county roads here locally I just pull over and let the "Nascar drafters" go by.